fix: do not mutate caller-provided client_kwargs in LinkContentFetcher

haystack/components/fetchers/link_content.py

@@ -143,7 +143,8 @@ def __init__(
         self.retry_attempts = retry_attempts
         self.timeout = timeout
         self.http2 = http2
-        self.client_kwargs = client_kwargs or {}
+        # Copy so that applying the defaults below does not change the caller's dictionary.
+        self.client_kwargs = dict(client_kwargs or {})
         self.request_headers = request_headers or {}
 
         # Configure default client settings

releasenotes/notes/link-content-fetcher-copies-client-kwargs-3e9a71c05d24bf18.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    `LinkContentFetcher` no longer adds its `timeout` and `follow_redirects` defaults to the `client_kwargs`
+    dictionary passed by the caller. The dictionary is copied before the defaults are applied, so sharing one
+    HTTP-client configuration between components is safe.

test/components/fetchers/test_link_content_fetcher.py

@@ -80,6 +80,16 @@ def test_init_with_params(self):
         assert "verify" in fetcher.client_kwargs
         assert fetcher.client_kwargs["verify"] is False
 
+    def test_init_does_not_mutate_client_kwargs(self):
+        """The caller's dictionary must not pick up the component's defaults."""
+        client_kwargs = {"headers": {"X-Request-ID": "example"}}
+
+        fetcher = LinkContentFetcher(timeout=10, client_kwargs=client_kwargs)
+
+        assert client_kwargs == {"headers": {"X-Request-ID": "example"}}
+        assert fetcher.client_kwargs["timeout"] == 10
+        assert fetcher.client_kwargs["follow_redirects"] is True
+
     def test_run_text(self):
         """Test fetching text content"""
         correct_response = b"Example test response"